1. Field of the Invention
The present invention relates to a photovoltaic device for use as a solar cell, photosensor or the like. The photovoltaic device uses hydrogenated amorphous silicon semiconductor as a photo-active layer for which hydrogen is added to silicon.
2. Description of the Prior Art
A photovoltaic device is constructed in such a manner that a front electrode, a power generating element and a back electrode are deposited in this order on an insulative and light-transmissible substrate. If light is incident on the device from the substrate side, a photo-active layer of the power generating element absorbs part of the light and generates a photo-voltage, and the generated photo-voltage is outputted.
Photovoltaic devices which use hydrogenated amorphous silicon semiconductor as a photo-active layer are well known. Hydrogenated amorphous silicon excels in thin film performance in comparison with single crystalline silicon, and therefore the area of the photo-active layer can be made larger while maintaining the same mass, resulting in an effective reduction in the cost. Thus, utilization of hydrogenated amorphous silicon in large-scaled solar cells is being promoted.
However, the photovoltaic device using hydrogenated amorphous silicon has problems in that the efficiency of photoelectric conversion is low in comparison with the photovoltaic device using single crystalline silicon semiconductor, and photo-deterioration (i.e. the efficiency of photoelectric conversion is reduced by intense light irradiation) is likely to occur (Japanese Patent Publication Laid-Open No. sho-54274/1984).